Leptoproduction of heavy quarks in the fixed and variable flavor schemes

We compare the results of the fixed-flavor scheme calculation of Laenen, Riemersma, Smith, and van Neerven with the variable-flavor scheme calculation of Aivazis, Collins, Olness, and Tung for the case of neutral-current (photon-mediated) heavy-flavor (charm and bottom) production. Specifically, we examine the features of both calculations throughout phase space and compare the structure function ${\mathit{F}}_2$(x,${\mathit{Q}}^2$). We also analyze the dependence of ${\mathit{F}}_2$ on the mass factorization scale μ. We find that the former is most applicable near threshold, while the latter works well for asymptotic ${\mathit{Q}}^2$. The validity of each calculation in the intermediate region is dependent upon the x and ${\mathit{Q}}^2$ values chosen.